1. Field of the Invention
The present invention relates to a method and an apparatus for a subband scheduling in a wireless communication system.
2. Description of the Related Art
When there is a shortage of allocable radio resources due to a load, a conventional evolved NodeB (eNodeB) (hereinafter, referred to as a “cell”) limits access of an additional terminal and limits services of terminals which are currently accessing the cell in order to reduce an amount of traffic throughput of the cell so that a cell load may be reduced. A cell in an overload state can use a Call Admission Control (CAC) method and a Quality of Service (QoS) based control method to improve a cell throughput.
The CAC method is a method of determining whether a call of a terminal attempting access to a cell is accepted according a cell load. When the CAC method is used, a cell calculates a load amount additionally generated by a service required by the terminal when the terminal requests access. Furthermore, when the cell determines that the calculated load amount may be processed by the cell, the cell accepts a request for a call acceptance of the terminal. Accordingly, when the cell is in an overload state, the cell blocks a terminal attempting access by using the CAC method, which prevents a cell throughput from being reduced.
The QoS based control method is a method of blocking a terminal attempting access based on QoS. A cell distributes limited radio resources to terminals that are each requesting different services. The cell first allocates the limited radio resources to a terminal requesting a service requiring high QoS by performing QoS scheduling. Accordingly, when the cell is in an overload state, a terminal provided with a service requiring low QoS cannot be allocated the limited radio resources and thus the terminal cannot be continuously provided with service.
As described above, in the prior arts, in order to solve a problem such as a cell throughput decline, the cell in an overload state reduces the number of terminals, which are currently accessing the cell. As a result, a problem occurs in that a transmission data amount is reduced or QoS that is provided to a terminal is deteriorated.